Is Dynamic Left Ventricular Dyssynchrony a Novel Surrogate Marker in the Patient with Hypertension?

Abstract

REFER TO THE PAGE 174-180 Recently, dynamic left ventricular dyssynchrony (LVD) using exercise echocardiography (ExE) become a promising method in many cardiovascular disease, because it can unveil the pathophysiology, can predict the prognosis and also would be a possible surrogate marker in the treatment monitoring.1),2) Especially in the field of cardiac resynchronization therapy, it would be a useful tool for patient selection, the prediction of response and optimization method during exercise.3) Although dynamic LVD can be measured by simply manipulating loading condition using sublingual nitroglycerine and leg-raising maneuver,4),5) ExE can be provide more additional information about myocardial ischemia, diastolic function, pulmonary hypertension and exercise capacity. The presence of left ventricular hypertrophy (LVH) and concentric remodeling is related to the prognosis of hypertensive patients. However, there were few report about the relationship of LVH and dynamic LVD. Seo et al.6) reported that systolic LVD during exercise is significantly associated with the degree of LVH in hypertensive patients. Although dyssynchrony was impaired in both LVH and non-LVH group at resting, exercise could differentiate these. Systolic and diastolic dyssynchrony were exaggerated more in LVH group compared to non-LVH one. And, as we expected, the presence of LVH could limit the exercise duration even adjusting for age, sex and diastolic dysfunction. It means ExE can provide a valuable suggestion between the pathophysiology of hypertensive LVH and exertional dyspnea. As authors described in discussion, hypertension impairs left ventricular function not only by influencing myocardial function, but also by impairing left ventricular synchronicity. Other interesting finding in this article is about the gender difference in LVD. Although they do not perform a subgroup analysis, transmitral E/mitral annular E' ratio at 50 watts of exercise was much more elevated in women compared to men, and the standard deviation (SD) of 12 segments the time from Q wave to myocardial early diastolic velocity (TPe) at peak exercise as well as modified SD of TPe (calculated considering heart rate) at peak exercise was very prolonged. It explains short exercise duration because women may be vulnerable to increase left atrial pressure and diastolic dyssynchrony at exercise. It may suggest the difference pathophysiologic mechanism on the progression of hypertensive heart disease in female compared to male. It need a further future investigation about that. In conclusion, dynamic LVD through ExE is probably one of the important topics in the hypertensive heart disease, because it will provide prognostic information and could be a surrogate marker for treatment monitoring.